Manufacturing soap



Patented Aug. 28, 1945 NT OF FIC'E MANUFACTURING SOAP Walter Russell Trent, North Arlington, N. J., as-

signor to Colgate-Palmolive-Peet Company, Jersey City, N. J a corporation of Delaware N Drawing. Application March 25, 1942, Serial No. 436,102

3 Claims.

' leaving glycerine in solution which is thus separated from the soap. If more of the glycerine is to be removed, successive washings, resulting in considerable aqueous dilution of the glycerine, must be employed. The soap is put in a crutcher, where his mixed with any desired adjuvant material, and. may then be framed or plodded and cut, or run in a plastic condition to steel rolls for flaking. The flakes may be left in this condition or may be ground. The plastic soap may also be forced through a nozzle in a spray tower to form beads or other finely divided particles. Continuous or semi-continuous processes of soap making have been provided, but high temperatures and/or numerous washings are also employed in these for removing glycerine from the soap.

Recently, it has been taught to split fats or oils by hydrolysis with water toobtain free fatty acids, and then to saponify these acids. Free acids react very quickly and vigorously with alkaline agents, as compared with the long process of saponifying fats and oils, but it is difficult to control the reaction and the condition of the product at this speed. Contact of freeffatty acids, particularly unsaturated acids, with air, even at moderate temperatures, causes the formation of dark oxidation products which tend to discolor soaps. Furthermore, the use of free acids requires that expensive, corrosion-resistant equipment be employed.

It is an object of the present invention to provide a rapid and economical process for making soaps, wherein lower alkyl mono-fatty acid esters are employed.

It is another object of the invention to provide a novel process of manufacturing soap of controlled water content.

a It is also an object of this invention to provide a novel and improved method for the continuous manufacture of soap from fatty acid esters of lower monohydric alcohols.

The invention also contemplates the provision of a novel process for the preparation of soap in granular, globular or other comminuted forms.

A further object of the invention is to provide a novel process for the direct and continuous preparation of superfatted soap of pleasant odor substantially devoid of glycerine and possessing desirable properties.

According to this invention, soap is prepared by mixing a fatty acid ester of a lower monohydric alcohol with an alkaline or saponifying agent, the ensuing reaction being carried out at atmospheric, superatmospheric, or reduced pressures and the monohydric alcohol liberated being flashed therefrom. The materials are preferably reacted at somewhat elevated temperatures and under superatmospheric pressure and then flashed I into a lower pressure chamber to volatilize the in such proportions as are determined by the alcohols, as well as some or all of any solvent (including water) employed. A subatmospheric pressure is advantageously employed in the flash chamber to remove from the product alcohol liberated in the reaction. The reaction is preferably carried out as a continuous process, operating from a continuous method ofproducing monoesters by alcoholysis of fats and fatty oils, using a measuring or proportioning device for mixing the monoesters with the alkaline agent operator, and then continuously passing them to a saponifier, as will be described in more detail infra.

In selecting fatty acid esters for use in the present invention, it is preferred to employ fatty acid esters of short chain monohydric alcohols, especially of alcohols having a boiling point in the presence of excess water of lower than C. at atmospheric pressure, and preferably the lower alcohols having 1 to about 6 carbon atoms I to the molecule. The fatty acids are preferably those having about 12 to about 20 carbon atoms, and mixtures of the esters may also be used. Mono-fatty acid esters of polyhydric alcohols may also be present in admixture with monohydric alcohol esters. Esters satisfactory for use in the process of the present invention include ethyl laurate, methyl stearate, ethyl margarate, propyl oleate, ethyl esters of coconut oil fatty acids, isopropyl esters of tallow fatty acids, methyl esters of tall oil fatty acids, butyl palmitate, tertiary butyl laurate, methyl arachidate, amyl myristate, isobutyl esters of cottonseed oil fatty acids, benzyl palmitate, and other monohydric alcohol esters. Among the monoesters of polyhydric alcohols which may be'present in admixture with the esters of monohydric alcohols are be used for saponifying these esters include sodi- ,um and potassium hydroxides, carbonates; .silie cates, etc., pyridine, methylmorpholine, piperidine, alkyl amines, alkanolaminesand other-or ganic and inorganic bases andjalkaline 'materials, and mixtures of these. The alkaline agent flashing into a zone at still lower pressures. monoester and alkali, preferably preheated to a desired temperature, are automatically proportioned and delivered, preferably continuously, to

may be introduced in aqueous solution, in alcoholic solution, or in solutions of other solvents, w 1.

or may be substantially anhydrous and/or substantially undiluted. The amount of solvent introduced With the alkaline or saponifying agent has a bearing on the water or organic solvent content of the finished product;

The process of the invention can be carried out by intimately. mixinga lower alkyl mono-fatty acid ester with a predetermined. amountpf an alkaline agent in a, reaction vessel. The heat of reaction may alone beSUfilCiBnl') toraisethe mixture-t the desired'temperature, depending upon the materials employed and subsequent operating conditions, or heatfromexternal sources may be supplied. Either or. bothofthe reactants may be preheated by steam or other means before being run into the vessel and/orthe mixture may be heated during and/or after admixture. and alcohol are thereby formed, and the alcohol is removed from the soap inavapor separation chamber. z

The operation of-th'is processicanbe carried Soap?) a mixing vessel where the ester is saponified under reduced pressure. The mixing vessel may be supplied with heat transfer means, such as a jacket, for heating or coolin as' required, and

' the solvent for the alkali, as Well as the alcohol liberated by the reaction, may be partially vaporized under the existing pressure conditions, whether subatmospheric, atmospheric or superatmospheric. Regulation of the temperature of the reaction mass is a factor in determining the amount of solvent and/or alcohol volatilized.

After flashing, the soap, dried or partially dried,

can be removedv from the vapor separation or flash vessel and collected.

An advantageous method of operation is to mix the reactants in a mixing vessel under atmospheric pressure and then to pass the products of the reaction to a separation chamber under vacuum. The materials may be reacted in a continuous mixer, such as aplodder, having its discharge under vacuum,. and .the comminute'd product therefrom may be passed through another continuous mixer or plodder to insure com-.

plete reaction and to discharge the product into the atmosphere in. desired form, such as bars fibers, tubes, or grains.

The monoesters and saponifying agents may also be reacted at an elevatedtemperature and under pressure and then flashed into a separation chamber at a lower pressure, Whether superatmospheric, atmospheric or reduced, thereby-vaporizing the solvent, if used, and the alcohol formed in the reaction. A suitable condensation system can be provided to recover the vaporized materials. In vaporizing the hydroxylatedprodout continuously by. contacting a monoester Withiif s of reaction, t e sap nifi ati n of t a saponifying agent under. conditions'of temperature and pressure adaptedforsaponification of the ester. The temperature of the saponification mixture may be Variedover acwide range, de-

pendingupon the type of ester to, be saponifiedfli;

the amount of Water and/or other solvent present, and thetype of .product desired. Even at only slightly elevatedtemperatures, the reaction rates are relativelyhigh, ascompared with polyesters, such as fats and. oils. employed is partially controlled by the pressure used. Th s. superatmospheric. pressures of; up

to atmospheres and even higher can be used,

esters aflords great advantage over saponification of the glycerides or other natural esters,

since the alchols liberated can bevaporized for recovery at much 1ower temperatures and with far less difiiculty than is possible with glycerine.

Where the reactants employed are nearly. anhydrous, considerably lower temperatures ca nbe The temperatureflio employed for removal of solvent than are possible with soap made from free fatty acids, as the lower alcohols, including methyl, ethyl,

propyl and isopropyl alcohols, can be vaporized :below the temperature required at a given presalthough pressures of about 2.0 to about 60 pounds per square inch absolute are: preferred; In gen-L eral, theelevated temperature. at which the sapdm'fication is carried out may vary from about to about 200 C., although temperatures of about 50 to aboutli-C. and pressures of about 20 to about pounds per square inch absolute are preferred. Higher pressures can be employed butin mostcases are unnecessary, frequently contributing diificulties of operation and sometimes leading to higher, temperatures, which may havea tendency, particularly. with unset- '65- sure for the'vaporization of either water orv glycerine. boiling in the presence of sufficient water, than glycerine and/or water anclrequires less heat to in the product to provide a superfatting agent therein, and such unreacted residue provide suclosed by the prior art.

perior, more stable and sweeter-smelling superfatting materials than are the fats andoilsdis- By operating at low temperatures, the excessfatty acid ester can be left in the soap, even though substantially allof the liberated alcohol is volatilized;

acting -materialsunde vacuum condition and f The ester and the. alkali solution-may be force The Since the lower alcohol-liberated is lower- The pipeis preferably equipped with a when using plastic or viscous mixtures or may 2 be coiled for-less viscous mixtures. The materials ,arethoroughly contacted in the conduit, and,

operating preferably continuously, the reaction product can be discharged to a low pressure zone,

. preferably through a constricted outlet or nozzle.

. Heat may be supplied to the pipe, if necessary, to

: raise the temperature'of the alcohol and of the -wateraor other solvent in the'pipe to, the vaporization point at the pressure in said pipe, and the temperatur.e and pressure at any point in the pipe may be kept substantially constant or may -be varied'in a cyclic manner for the purpose of :creating greater turbulence in the reaction con- .duit by alternately-establishing and destroying a vapor phasetherein. Upon flashing into the low qpre'ssure zone, the heat of the reaction product is employedto vaporize the water or other solvent and thealcohol at the low pressure of the separation chamber, and the vaporized material goes off at the top while the solid soap, having at least a portion of water and other volaxtilematerials removed, falls to the bottom. Variaous means may be employed for facilitating the 1.reaction. of the alkaline. agent with the ester. Thus, it has been found convenient to jet the alkaline solution into the liquid ester and to employ ,a size, and shape of reaction pipe which provides a;hi'gh degree of velocity and turbulence for contacting the materials.

The moisture or solvent content of the finished product can be modified by regulating the heat suppliedetol the reaction mixture by preheating the reactants-and/or externally heating the conduit or, otherwise; The temperature required is ;.farxbelow that necessary for glycerine recovery in -saponifying, glycerides. Therefore, although 1; possible, ,it is unnecessary and less desirable to .go to the temperature of molten anhydrous soap pr'higher in, order'to vaporize the monohydric ,jalcohols' liberated, as they or their aqueous azeotropes are lower boiling than water.

Fur-

. thermore, itis possible to recover the soap in Moreover, shortsition, canbe employed. Where a dry soap substantially free of alcohol and solvent isdesired, alcoholand water and/or solvent are preferably atleast partially vaporized before the soap formed ventersqthe low pressure Zone. An increase in heat supplied causes more solventand alcohol to vaporize and thus increases the solvent vapor and/or alcohol vapor in the conduit. Thisincreasesthe pressure and hence the temperature, vvhieh is thetemperature of thesaturated vapor -at,the higher pressure. A screw conveyor can be advantageously employed for advancing solid soapinthe reaction conduit. For improved re- ;resultsin obtaining, forexample, a very dry, al-

cohol-free soap- (say, of less than about 2% --.;moisture or ,alcohol content), the soap may be treated with superheatedsteam either during discharge into the flash chamber or afterwards, as will be describedinfra.

1 ISoap. builders, inert materials, anti-oxidants, jetcz, inaybeaddedto, the monoester and/or to .the: saponifying agent before contacting. Since.

product of the present process. also possible to employ, if desired, volatile, wa-

the washing steps, in general use in prior art practice, need not be employed, these modifying agents, even ifwater-soluble, are found in the Conversely, it is ter-insoluble materials, such as low-boiling petroleum hydrocarbons, the presence of which in the final product might be disadvantageous for certain uses, since they do not appear in the finished product. Certain saponification accelerators, while not ordinarily required for saponifying monohydric alcohol esters, fall in this category and may be added, if desired. l

The vaporized water or other solvent and the vaporized alcohol liberated in the reaction are withdrawn at the top of the separation chamber and together pass to a condensation system. The temperature of the chamber and of the passage to the condensers is maintained above the dew point of the vapors. jointly condensed, but it is preferred to provide at least one condenser for each material to be condensed or to employ a fractionating column. The condensers may be of reflux, jet or other suitable type. Recovery of solventand/or alcohol in relatively pure condition is facilitated by this means.

The pressure within the separation chamber is easily regulated by control of the condenser temperatures and of the pressure beyond the condensers. The pressure within the chamber is preferably low enough to provide rapid vaporization of the highest boiling material to be withdrawn as a vapor. This depends in part upon the temperature and degree of vaporization of the reaction mixturedischarged into the chamber from the nozzle, as the higher this temperature and pre-volatilization, the higher can'be the pressure within the chamber.

By contacting the reaction mixture, momentarily and just before discharge into the low pressure or flash zone, with an inert gas at a considerably higher temperature, less heat need be supplied to the reaction conduit and/or a higher absolute pressure may be employed in the separation chamber. The contact of the reaction mixture with an inert gas, such as superheated steam, kerosene vapor, carbon dioxide, flue gases,

- stack gases, etc., is preferably made at extremely high velocity and for a minimum time period before introduction into the flash chamber. The contacting can advantageously be accomplished by a nozzle designed to permit intimate but only momentary direct contact and a minimum of indirect contact before emission into the flash chamber. Employing this modification, the length of the reaction and/or heating conduits can be appreciably shortened, if desired, and less heat need be supplied thereto by-external heating of the conduit and/or by pre-heating of the monoester and/or the saponifying agent.

In another procedure, it is possible, by means of superheated steam or other inert gas, to supply sufficient heat at an optimum temperature and velocity in order to effect instantaneous saponification, even under anhydrous conditions, along with flash-distillation of the materials to be withdrawn as a vapor. This procedure avoids plugging of pipes and-nozzles, because the reactants are not mixed together for a sufiicient time before flashing for saponification, especially under anhydrous conditions, to take place to any substantial extent and because the mixed reactants are not excessivelyheated before introduction into the nozzle, where they attain high .ve-

The vapors may be conlocity and adequate heat in momentary time before their discharge into the flash chamber. Although the flashchamber may be'operated in any case at'atmospheric, elevated or reduced pressure, depending upon the vapors to be withdrawn and the temperature of the'discharge from the reaction conduit, it will be understood from theforegoing that the useof superheated steam or other inert gas at a very high temperature raises the pressure at which the flash chamber" can be operated. I e

Operation according to this latter procedure is simple in that only a few process steps and a small amount of equipment are necessary, and, furthermore, s'uch operation utilizes the chemical heat of saponification. Great economy of operation is achieved by thus getting additional heat from the-saponification after contact with'the superheated steam and adsorption therefrom, in-

stead of first sap'onifying' the monoester and then heating the soap before contact with the steam. In practice, the proportion of superheated steam introduced into the nozzle in these various modifications can be so regulated that a dry product or a hydrated product can be produced. The product may be made 'a more or less finely divided condition, which permits its ready transformation into flakes or other physical forms, for example, by passing between a pair of properly spaced rolls, or by pressing into cakes, 'or by other means, with or without addition agents. I

Adjuvant materialsmay be admixed with the soaps th'usfo'rmed' by mixing them with the monoesters and/or the sa'poniiy'ing agents before flashing, by simultaneously flashing a second solution containing such adjuvant materials, and/or by mixing the final product therewith. Such adjuvant materials may include fatty acid soaps prepared bythe same or other methods/' resin acid soaps, naphthenic-an'd alkylated naphthenic acid soaps, sulphated and 'sulphonated organic compounds, alkaline soap builders, watersoluble, water 'softening' compounds of the acids of phospho'rusf'and 'other salts including sodium carbonate, sodium silicates, trisodium phosphate, borax, sodium tetraph'osphate, sodium bicarbonate, sodiumsulpha'te, sodium chloride, .sodium acetate. sodium" hypochlorite, sodium' thiosulphate, sodium perborate, sodiumtartrate, sodium citrate and sodium oxalate, and the corresponding ammonium, substituted ammonium and po- 'tassium salts of the corresponding acids; insecticidal, germicidal; styptic and medicinal agents,

including aluminum chloride, mercuric chloride pine oil; decalin and tetralin, and the like. The

type of addition agent will'depend upon the ultimate use of the new composition. T i

The reaction product from 'the vapor separa tion chamber may be discharged into a cooling element orconduit, where it is partially cooled while under pressure, thus partly solidifying the soap. It may then be passed to an extrusion orifice, where 'it' maybe cut into bars. 'Du'ringthe cooling operation, butwhilethe soap product is still quite liquiddue to the' pre'sence' of water 1118111161; conduit is ejected through a nozzl into a separation. chamber under vacuum under suitable conditions, as disclosed supra, to'fiash ofl subbe in liquid, plastic or semi-plastic-state.

injected into the soap.

In practica'when producing bars and cakes'of soap, it is preferred so to control the cooling of the soap in the cooling element that the soap is at least partially liquid upon passing to the-extrusion element. This element, having anoriflce of cross-section approximating that of the de- 1 sired soap cake, is preferably of extended length and jacketed for carrying acooling fluid for fur- .ther cooling of the soap. The cooling of the soap may thus be" substantially completed inthe extrusion orifice during its passage therethrough.

In another but not preferred modification, the soap may by hydratedby steam'in' the following The mixture train the saponification stantially all water and/or other solvent and substantially all alcohol therein whilst maintaining the temperature sufiiciently high for. the soap to The soap, substantially anhydrous and non-alcoholic, is then passed to a cooling element, preferably a coil, and steam is injected into thesoap during its passage either into or through the cooling element. The soap is then passed to the extrusion element as aforesaid. This providesa rela tively simple method for obtaining a desired moisture content of product, as the proportion between the amount of water fed to the boiler for conversion into steam to the amount of nionoester fed to the saponiiication conduit determines the percentage of moisture.

Where a fatty acid ester of 'an'alcohol having 1a boiling point above that of water and/or where asolvent for thesaponifying agent having a boilcohol and/or solvent can be retained, if desired,

in a substantially anhydrous soap. 'I'hgtemperature (or vacuum) in the flash chamber, for example, can be lowered enough so that all of such alcohol and/or solvent is not vaporized but a -p0rtion falls out with the soap. The temperature selected is higher than the boiling'point o'f water at the particular pressure in the chamber but -lower than the boiling points of the" alcohol.

and/or solvent, Similarly, where the fatty acid ester of a low-boiling alcohol is used,- the temperature and pressure conditions inthe" flash chamber can be regulated so as to remove sub stantially' all of the liberated low boillng' alcohol, while retaining at least part of the water or other solvent. i

If desired, the soap, instead of beingforced through an extrusion outlet after flashing, may be ejected through a spray nozzle or spinner bowl into a spray tower. Due to the lower pressure in thetower, the alcohol vapor, steam and air within the soap expand to give beads,and spongy granules. Cooling of'the mixture from the vapor separation chamber, as in the manner described, before dischargingit into the spray tower may be used to control the amount of alcohol vapor or of steam or solvent vapor produced and hence the amount of alcohol, water or solvent permitted to remain in the soap. A floating granular soap may be made by this treatment by injecting compressed air into the soap during'its passage through "the cooling element and by controlling" the moisture or alcohol content. The soap, though cooled, is delivered to the spinner bowl or spray nozzle in the liquid, lastic or semi-plastic state, largely depending upon the extent of cooling, and at a temperature of about 105 to about 250 F. Upon atomization, the particles come into Substantially granular and/or hollow soap particles are obtained.

The soap may be treated with brine after flashing, if desired, and may then, after separation of the brine and/or a nigre, be passed through a-secondary heating coil, where the temperature and pressure are raised, and water in the soap is vaporized and removed to the extent desired in asecondary flash or finishing chamber. It will be understood from the foregoing that the brine treatment may be applied to the soap directly after its formation in a batch reaction vessel before flashing, or, in continuous operation, it may be applied after formation of the soap in the saponification'conduit, part of the alcohol and solventbeing removed with the brine and impurities before reheatin and flashing the purified The soap may be passed to drum dryers to produce flakes and ribbons. Since drying can be accomplished by other means, as set forth herein, chilling rolls may instead be provided, Where it is desired to form a friable soap, sudden chilling has been found to be advantageous. The

drier soaps are more friable than those containing considerable amounts of water, and very dry soapsare frequently self-disintegrating, breaking up into small grains upon cooling. Thus, after removal of alcohol and water or other solvent in the flash chamber, the soap at the bottom oft-he chamber may be withdrawn by means of sealed conveyors preferably operated under subatmospheric pressures. If the soap is discharged into the flash chamber at a high enough temperature, no additional heat need be supplied; otherwise,

the chamber may be jacketed for adding suflicient heat to keep the soap in a fluid condition, or superheated steam may be admitted. The conveyors may also be jacketed, and a plurality of jackets may be employed, so that a heating fluid may be passed through the first part of the jacket (to aid in maintaining a sufliciently high temperature within the flash chamber), while the second part carries a cooling fluid to give thesoap a sudden chill. Another and/or additional means of suddenly cooling may be employed by injecting water directly into the soap while in the conveyor, preferably at a part of the conveyor non-contiguous to the outlet of the flash chamber.

While the removal of alcohol formed with the soap acts to cool the soap by the evaporation of the alcohol in the vapor separation chamber, additional water or other liquid may be injected into the soap at temperatures above the boiling point of such injected liquid at the pressure in the vapor separation chamber, the vapors being removed as formed so as not to hydrate the soap. For example, water introduced is immediately vaporized at the temperature of the soap, cooling the soap at a low pressure and in the absence of air, and the water vapor may be passed into the flash chamber. If it is desired to hydrate the soap to any degree, additional water may be injected into the soap, either at this point or farther along, controlling the amount injected. ,The cooling jacket can be employed for condensing vapors before discharge. Even where considerable hydration is de- "sired and, sufficient cooling can be obtained by circulating a cooling fluid in the conveyor jacket, it may nevertheless be advantageous to vaporize part of the injected Waterfor thepurpose of obtaim'ng uniform distribution of the water added.

"Such uniformity may also be obtained by agitation inv the conveyor. Economy-of operation may.

be achieved by using one of the reactants, preferably the monoester, asthe cooling fluid in the v, jacket. This serves to preheat the reactant before 15' its passage to the saponification conduit.

Steam introduced into the separating or flash chamber can also be employed to add heat and to keep the soap in fluid condition. The introduction of superheated steam makes it possible to 20* operate the flash chamber at a higher pressure. The steam may be discharged into the chamber at any point therein, but it is preferred to have the inlet near or surrounding the soap discharge nozzle from the saponification conduit. It is also possible to attain the desired temperature by steam jacketing the pipe containing'the entering soap. The soap discharge inlet may be directed so that the incoming soap impinges upon the wall of the flash chamber, flowing down rela- 30' tively slowly and thus aifording ample opportunity for vaporization of alcohol and water or other solvent. While a nozzle may be employed, if desired, it is not required in this modification, es-

, pecially if the reacting mixture is moved into a mixing machine, such as a pump, a screw coning conduit may be used after this mixing to raise the temperature before admission to the vapor separation chamber. v

The following examples described herein are merely illustrative of the present invention, and it will be understood that this invention is not limited thereto.

Example I A mixture of about 240 parts by weight of the methyl esters of coconut oil fatty acids, about '78 parts of the methyl esters of olive oil fatty acids,

: and about 75 parts of the methyl esters of tallow fatty acids is heated to about C. and pumped into a reaction vessel. About 170 parts of a 42 B. solution of sodium hydroxide at about 100 C. are also pumped into the vessel over the same period, the vessel being under a pressure of about 80 pounds per square inch absolute and equipped with an eflicient agitator. The mixture is run through the vessel in about 3 to about 5 minutes, and the temperature of the reaction mixture rises to about C. The reaction mass is then discharged into a vapor separation chamber, which is under a vacuum of about 27 inches of mercury, and the methyl alcohol liberated in the reaction together With part of the Example II About 8 P t pe ho rwe e -the me h l:

esters of coconut-oil fatty' acids' at about 45C. are contacted with about parts per hour of a B. aqueous solutionof sodium hydroxide at about the same temperature and. with an aqueous solution containing about 0.5 part per'hcur of tetrasodium pyrophosphate' in a short coiled conduit designed to' provide turbulent mixing during a short time interval, say of a few second's. The conduit has a constricted or nozzle outlet, providing a pressure of the reaction mixture ofv about 3 atmospherespand about 75 parts per hour of superheated steam 'under a pressure of about 1 5 atmospheres are injected into the reaction mixture just inside the nozzle'j 'The [nozzle is located infa vapor separation chamberoperated under a vacuum of about 27 inches of mercury'and jacketed to maintain a temperature of about 160 C; Substantially all of the Waterand the inethyl alcohol liberated by the reaction are flashed and'removedfrom the chainher. The soap, substantially anhydrous and nonalcoholic and containing tetrasodiurnpyrophosphate, is in granular-form" and is removedby means of asealed conveyor.

Example III Abo t i Parts by weight per hour of the ethyl.

esters of coconut oil fatty acids mixed with about 20 parts perhqur of the ethyl esters of tallow fatty acids are proportiQned into a reaction conduit with about parts per hour of a 25" B. solution of caustic soda. The conduit is under a pressure of about 40 pounds per square inch and is raised to a temperature of about 150 y rect n e n of .steam m a fim steam n The cond t is ,sum iently lon o ha t e reactants Pass rou h in abou t e y minutes. The material in the conduit is discharged into a jacketed vacuum chamber, wherein'the ethyl alcohol liberated and midst of the water are vaporized, and removed. Soap in gran ularlforrn and containing about 12% moisture is continuously removed from the bottom of; the;

chamber by meansof a sealed conveyor.

Although .the present invention has been described with reference to particular embodiments x andexamples, it will be apparent to those skilled in the art that variations and modifications of this invention can be made and that equivalents can be substituted therein Without departing frqni the principles and true spirit of the invention.

Such Variations and "modifications are believed to be within the scope of the present specification,

alkyl monohydric alcohol and a. saponlfyingr agent through a mixing zone at .an elevatedternjperature and under a superatmospheric pressure,

and discharging the reaction mixture into a lower pressure zone, the improvement which comprises alternately establishing and destroying a. vapor.

phase in said mixing zone. 3. In the process of producing soap comprising continuously passing a .fatty acid ester of alQWr alkyl monohydric alcohol and a saponifying.

agent through a mixing zone at'an elevatedtcmr perature and under a superatrnospheric pressure, and discharging the reaction mixture into alower pressure zone, the improvement which comprises alternately raising and lowering the temperature and pressure within said mixing zone in' a cyclic manner. .r

WALT-ER. R SSELL 

